High-speed wire tension device



Sept. 25, 1-951 B. B. SCOTT I HIGH-SPEED WIRE TENSION DEVI Filed March 22, 1949 ncor': Ber ami n B. Scott,

by His Attorneg.

Patented Sept. 25, 1951 HIGH-SPEED WIRE TENSION DEVICE Benjamin B. Scott, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application March 22, 1949, Serial No. 82,887

7 Claims. (Cl. 24245) My invention relates to high speed machines for winding precision wire resistances and, more particularly, to a device for constant maintenance of tension between the winding machine and the reel supplying wire to that machine.

Precision resistances are manufactured by a winding machine which accurately places turns of wire on a supporting member according to a master resistance. In order to have uniform resistance characteristics in the finished resistance, the wire must be wound with uniform tension in the turns since the resistance of the wire varies directly with wire tension. Also, finished precision resistances generally have the wire turns pressed flat against the supporting member and secured there so that the wire turns will remain in the position in which they were wound. To insure that the wire of the turns is under substantially even tension and that the pressing operation does not displace the brushing edges of the turns, a substantially uniform initial stress below the elastic limit of the wire material is introduced in the turns of wire by maintaining the wire under substantially uniform tension during winding so that during the pressing operation any slack appearing in the wire can be taken up as the wire returns to its unstressed length.

As wire is wound directly upon a supporting member from a reel having reverse torque restraint, the rotating member exerts a force upon the wire to pull it from the reel. This force and the opposing rewinding force applied to the wire by the torque member, cause tension in the feed wire. Supporting members vary in form from a cylinder which exerts a constant pull on the before winding can 'begin. As pull is applied to the wire by the section against the oppositely moving rotational inertia of the winding reel means, shock tension stress results in the wire which is likely to be above the elastic limit of the metal such that if breakage does not occur, strains are produced that cannot be normalized in precision resistances except at destructive temperatures. Such strains cause the resistivity of the wire to increase unpredictably beyond calculated values so that wire tension must be maintained at uniform levels throughout the winding of cards and irregular dynamic stresses must be limited to values well below elastic limits.

The object of my invention is to provide a device that will absorb the sudden changes in tension between a high speed precision winding machine and a supply reel provided with a rewinding torque means.

In my invention, a reel supplied with a means for furnishing a constant, rewinding torque is wire to a flat member having an overswung section in which the winding axis is wholly outside the section. When an overswung section is wound, a pull is applied to the wire during the half revolution when the section is moving away from the guide pulley and the wire moves in the direction away from the reel. During the second half revolution, the section is moving towards the guide pulley, and the wire moves towards the reel.

The inertia of the wire supply reel and its associated torque means, prevent instantaneous response to change in winding tension except at very low inefficient speeds, so that at the instant the overswung section moves towards the guide pulley, an instantaneous slack is formed in the wire. At the instant of the beginning, of movement of the section away from the guide pulley, the torque member is still rewinding wire'on'the reel so that the wire must be reversed in direction tension. A counter-torque is applied to the wheel.

by a weight suspended upon a wire attached to the circumference of the wheel. suspending wire is led around a sector of the circumference of the wheel between the flanges so that the weight hangs freely from the circumference of the wheel opposite the arm.

A weight and pulley system is attached to the wheel so that the force of the weight tends to maintain the arm in a horizontal position.

An air dashpot mounted on the winding head is attached to the circumference of the wheel to stabilize the system against harmonic oscillation and inertia shock.

For a better understanding of my invention, reference is made to the accompanying drawing in which Fig. 1 is a schematic isometric view of a particular embodiment of the high speed tension device shown in conjunction with a winding machine.

Fig. 2 is a vertical elevation of the same combination. a r

The weight Referring to the drawing, wire I from the reel 2 traverses the directional pulley 3, the guide pulley 4 and i wound upon a supporting member by the winding machine 6. A torque means 1 continuously supplies a rewinding force to the wire I. As the resistance is wound, the winding head 8 is moved along a guide rods for the length of the supporting member 5 by the lead screw III which may be rotated by a motor (not shown). The reel 2 and the pulley 3 are rotatably mounted upon the winding head 8, the pul ley 3 rotating about the axis II fixed with relation to the axis of reel 2. A wheel I2 to which is rigidly attached a radial arm I3 upon which i the pulley 4 is rotatably mounted, oscillates about the axis II. Wheel I2 may be considered as an integral hub of arm I3.

Instantaneous variations in winding tension are compensated by the oscillation of the arm I3 about the axis II from a normally horizontal position to vary the length of wire'path. The weight M is suspended upon the cord for wire I5 attached to the wheel I2 at the point I6. The strand I5 extends partially around the periphery of the wheel and is held in place bythe flanges II of the wheel so that the weight I4 hangs freely. V v

The value of the weight I4 is chosen so that it will counter-balance the arm IS in a normal horizontal position and, in addition, apply a wire tension equalling approximatelyedqa of the elastic limit of the wire being wound, When wire tension varies from this amount, the arm raises or lowers to increase or decrease the length of wire path in order to return the wire tension to the predetermined value.

With the weight I4 merely providing a dorm ter-torque to the torque acting through the arm I3, any change in wire tension would cause the arm to move to a new position and stay there until a succeeding change in tension occurred. A weight I8 is suspended upon the strand It at"- tached to the wheel I2 at the point 20; The strand is is threaded between the two pulleys 2| and 22 so that the force of the weight I8 biases the arm I3 to a horizontal position;

The weight I 8 is chosen so astjo exert a maximum tension of approximately 10 grains on the wire being wound. With this single value for weight i8 all of the diameters of wire commonly desired. to be employed may be wound merely by changing the weight I4, since the tension produced by the weight I8 is a relatively smallfrac tion of the total tension supplied by weights I4 and I3. H

With rhythmic reversals of tension sympga thetic with the periodicity of the arm I3, the a I3 would be liable to uncontrolled 'oscillatio s that would set up stresses capable of breaking 'the wire. Accordingly, an air dashpotteis p'ivotally mounted upon the winding head B'and pivotally attached to the wheel I2'at the point 24' to :stabilize the tension compensating system against uncontrolled oscillation and inertial ShO ck.

many modifications can be made, and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A machine for winding a filament of elongated material irom a supply reel onto a supporting member including means for applying a rewinding torque to the supply reel and reducing fluctuations in the tension in said filament arranged between said supply reel and said support comprising a counter-balanced tension compensating means having a radial arm rotatable about a fixed axis, a guide pulley rotatably mounted upon said arm, said pulley comprising a with said reel and said member a path for said filament, said tension compensating means beihg capable of alteringthe length of said path to compensate for changes in tension, and restoring meansengaging said tension compensating means tending to maintain said tension cempensating means in a predetermined normal position, and means connected for oscillations ofsaid armby a force increasing upon deviation from said normal position. n 2. A high speed tension device for a machine for the precision winding of wire from a supply reel uponla, supporting member, said reel being provided with rewinding torque means to preduce a rewinding force upon said wire, said supporting member supplying a force to said wire counter to said rewinding force to produce a tension in said wire, said device comprising a directional pulley rotatably mounted on 'n axis fixed with relation to the'axis of said reel, Qan oscillatable arm means rotatably. euntee th respect to said fixed axis, said means including 'a wheel, an axial arm rigidly mounted upon said wheel and a guide pulley rotatably mounted upon said arm, said pulleysproviding with said reel and said supporting mjembera path 'of variable length for said wire's'o that sudden changes in said tension are compensated by appropriate changes in saidpath, centering means cooperating with said wheel biasing said arm, to a normal horizohtal position, and means c'c'innekzted to said wheel to apply a force thereto increasing upon displacernent of said arm fromsaid normal position for dainpingosc'illation's thereof. v

3. A high speed tension device in a winding machine for precisioin mounting of wire upon'a supporting member from a su'p'ply reel, said reel being rotatably mounted upon the winding head of said machine and including rewindih'g torque means for said: re'el, said device comprising a directional pulley mounted upon said winding head and rotatable aboutan axis; a wheelpro vided with peripheral Qfianges mounted upon said winding head and rotatable about said axis, a normally horizontal arm rigidly attached" to said Wheel and radially. extendingtherefrom, a guide pulley rotatably mounted upon said arm, said pulleys forming a path for the wire, from said reel as said Wire is wound on said supporting member, the force uponjthe wire rremthe rotation of said member supplying a torque to said arm and thereby to said wheel, a first weight suspended upon a strand'attached to the circumference of said wheel so that said. weight is suspended from saidwheel oppositely from the normal horizontal position or said arm to supply acounter torquio' said wheel equal andoppo sitetc said torque; a second weight uspended frblna second strand atta'hedtdthe cirEuin-Q ference of said wheel, pulleys pivotally mounted upon said winding head, said second strand being threaded around said pulleys so that the force of said second weight tends to maintain said arm in its normally horizontal position, an air dashpot mounted upon said winding head and secured to the circumference of said wheel to dampen oscillations of said arm.

4. A filament tensioning device for maintaining filament tension within narrow limits during a rapid nonuniform speed of delivery of the filament comprising means for applying an initial tension to the filament, a pivoted arm, a pulley rotatably positioned on said arm remotely from said pivot across which the filament is guided from said initial tensioning means, at least one of the directions of the filament in approaching or leaving said pulley making an angle with respect to said arm to thereby exert a torque on said arm by reason of the tension applied to the filament by said initial tensioning means, and means for opposing said torque while maintaining a low inertia in said arm, comprising a weight fastened to said arm at a point near said pivot, the value of said weight being selectable for difierent desired filament tension values, a second weight attached by means of a tension member to a point on said arm displaced from said pivot for biasing said arm to a predetermined desired mid-position by exertion of a torque increasing in proportion to the displacement of said arm in either direction from said predetermined mid-position.

5. A filament tensioning device for maintaining filament tension within narrow limits during a rapid nonuniform speed of delivery of the filament comprisng means for applying an initial tension to the filament, a pivoted arm, a pulley rotatably positioned on said arm remotely from said pivot across which the filament is guided from said initial tensioning means, at least one of the directions of the filament in approaching or leaving said pulley making an angle with respect to said arm to thereby exert a torque on said arm by reason of the tension applied to the filament by said initial tensioning means, and means for opposing said torque while maintaining a low inertia in said arm, comprising a weight fastened to said arm at a point near said pivot, the value of said weight being selectable for different desired filament tension values, an arm oscillation damping device connected to said arm to exert non-linear damping forces increasing with increasing displacement of said arm from a predetermined normal position.

6. In a machine for winding nonlinear preoted arm with a wire guiding pulley positioned thereon at a distance from said pivot, the wire from said reel approaching said pulley in a direction parallel to said arm and leaving said pulley for application to the card in a direction substantially perpendicular to said arm whereby the wire tension provides a torque on said arm, a weight connected to said arm at a point displaced from said pivot in a direction opposite the position of said pulley for counterbalancing both the weight of said arm and said torque, a second weight attached by means of a tension member to a point" on said arm displaced from said pivot for biasing said arm to a predetermined desired mid-position by application of a torque increasing in proportion to the displacement of said arm from said mid-position, and an oscillation damping device comiected to said arm to exert damping forces proportional to the displacement of said arm from said mid-position.

7. In a machine for winding nonlinear precision resistors on noncircular resistor cards, a resistor wire tensioning apparatus for maintaining the tension on the wire being wound on the resistor card within predetermined limits, including an initial tensioning device for applying a predetermined initial tension to the wire as it is unwound from a reel, and a quick response automatic tension adjusting device comprising a pivoted arm with a wire guiding pulley positioned thereon at a distance from said pivot, the wire from said reel approaching said pulley in a direction parallel to said arm and leaving said pulley for application to the card in a direction substantially perpendicular to said arm whereby the wire tension provides a torque on said arm, a weight connected to said arm at a point displaced from said pivot in a direction opposite the position of said pulley for counterbalancing both the weight of said arm and said torque, a second weight attached by means of a tension member to a point on said arm below said pivot for biasing said arm to a predetermined desired mid-position, a guide for said tension member adjacent to said second weight for restricting ,horizontal movement of said second weight whereby displacement of said arm from said midposition horizontally displaces said tension member above said guide to raise said second weight, and an arm oscillation damping device connected to said arm for displacement thereby at a rate increasing upon increase in the displacement of said arm from said mid-position.

BENJAMIN B. SCOTT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,237,112 Parvin Apr. 1, 1941 2,315,332 Howe et al Mar. 30, 1943 

